1. Field of the Invention
The present invention relates to a binaphthol derivative useful for the optical resolution of amino acids or amino alcohols and for the optical transformation of amino acids from a D-form into an L-form, or vice versa.
The present invention also relates to a method of subjecting racemic amino acids or racemic amino alcohols to optical resolution using the above derivative, thus obtaining optically pure amino acids or optically pure amino alcohols.
The present invention also relates to a method of subjecting amino acids to optical transformation from a D-form into an L-form, or vice versa, using the above derivative.
2. Description of the Related Art
Optically pure amino acids and amino alcohols are widely used as ligands of asymmetric catalysts or as starting materials or intermediates necessary for synthesizing various pharmacerutical supplies and physiologically active substances, and are thus regarded as very important in industrial fields ((a) Coppola, G. M.; Schuster, H. F. Asymmetric Synthesis. Construction of Chiral Molecules Using Amino Acids; Wiley: N.Y., 1987; (b) Bergmeier, S. C. Tetrahedron 2000, 56, 2561-2576; (c) Noyori, R. Asymmetric Catalysis in Organic Synthesis; John Wiley & Sons: New York, 1994; (d) Helmchen, G.; Pfaltz, A. Acc. Chem. Res. 2000, 33, 336-345. (e) Ager, D. J.; Prakash, I.; Schaad, D. R. Chem. Rev. 1996, 96, 835-876).
With regard to the preparation of such optically pure amino alcohols, DE Unexamined Patent Publication No. 4341605 discloses a method of synthesizing optically pure amino alcohols from optically pure amino acids.
Unlike L-amino acids, D-amino acids do not naturally occur, but must be industrially synthesized using an enzymatic biocatalyst. In this case, attributable to the instability of the enzymatic biocatalyst and the high selectivity thereof to a substrate, the preparation costs are increased, and it is very difficult to produce various D-amino acids. Accordingly, various amino alcohols corresponding thereto are also difficult to produce, the preparation costs are very high, and the supply thereof is insufficient to meet the demand therefore.
Therefore, thorough research into methods of easily and inexpensively producing pure D-amino acids is continuously conducted ((a) Williams, R. M. In Synthesis of Optically Active a-Amino Acids; Baldwin, J. E., Ed.; Organic Chemistry Series; Pergamon Press: Oxford, 1989. (b) Williams, R. M.; Hendrix, J. A. Chem. Rev. 1992, 92, 889. (c) Duthaler, R. O. Tetrahedron 1994, 50, 1539. (d) Seebach, D.; Sting, A. R.; Hoffman, M. Angew. Chem., Int. Ed. Engl. 1996, 35, 2708. (e) Maruoka, K.; Ooi, T. Chem. Rev. 2003, 103, 3013.).
Favretto et. al. (Tetrahedron Lett. 2002, 43, 2581) proposed a method of synthesizing optically pure amino alcohol from chiral epoxide. However, this method is disadvantageous because of the use of expensive chiral epoxide and the poor yield, regioselectivity, and stereospecificity, thus making it difficult to realize industrial applications.
Recently, the optical resolution of amino alcohols by reactive extraction is regarded as an industrially attractive choice because it currently appears to be the most cost-effective process (Steensma, M.; Kuipers, N. J. M.; Haan, A. B.; Kwant, G. Chirality 2006, 18, 314.). Versatile chiral receptors were tested by N. Kuipers and Prelogs for chiral separation of a number of chemically related amino alcohols and amines by reactive extraction. However, the selectivities of most of the tested receptors were too low for commercial application, except azophenolic crown ether of Hirose whose selectivity approached to 5.0 (Naemura, K.; Nishioka, K.; Ogasahara K.; Nishikawa, Y.; Hirose, K.; To be, Y. Tetrahedron: Asymmetry 1998, 9, 563.).
Therefore, the present inventors have developed a method of forming an imine bond using a binaphthol derivative (Compound 1) having an aldehyde group to thereby recognize the chirality of a chiral amino alcohol or amino acid and transform L-amino acids into D-amino acids ((a) Park, H.; Kim, K. M.; Lee, A.; Ham, S.; Nam, W.; Chin, J. J. Am. Chem. Soc. 2007, 129, 1518-1519; (b) Kim, K. M.; Park, H.; Kim, H.; Chin, J.; Nam, W. Org. Lett., 2005, 7, 3525-3527).

The binaphthol derivative (Compound 1) has been invented based on the reaction mechanism of a PLP compound ((a) Shaw, J. P.; Petsko, G. A. Ringe, D. Biochemistry, 1997, 36, 1329-1342; (b) Walsh, C. T. J. Biol. Chem. 1989, 264, 2393-2396) acting as a cofactor in an enzyme called amino acid racemase.
The binaphthol derivative (Compound 1) is useful for stereoselectively recognizing chiral amine through the formation of an imine bond and separating amino alcohol into respective optical isomers, are surprisingly able to convert DL-amino acids into D-amino acids, which is very useful to produce D-amino acids or optically pure non-natural amino acids by a novel way.
The binaphthol derivative (Compound 1) reacts also stereoselectively with amino alcohol, forming an imine compound, the selectivity thereof ranging from 1:3 to 1:5. However, in the case where the selectivity is high, amino alcohol may be more easily separated into respective optical isomers. Hence, the development of novel binaphthol derivatives having higher stereoselectivity is required for a more efficient industrialization process for the resolution of amino alcohols. Furthermore, Chiral binaphthol derivative having chemical properties such as high stereoselectivity and favorable solubility in chloroform or ethyl acetate are especially required to be applied to the reactive extraction process which is regarded as economically cost effective process.